Compressor for refrigeration and air-conditioning and refrigerating and air-conditioning apparatus

ABSTRACT

A refrigerating machine oil including a refrigerating machine oil basis such as polyol ester oil and an additive polyol ester oil is mixed to a refrigerant including 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene or the like. A compressor for refrigeration and air-conditioning including the mixture charged therein is used. The composition of the additive polyol ester oil is 1 to 30 wt %. 
     The wear resistance of the compressor is improved, and the efficiency of a refrigerating and air-conditioning apparatus using the compressor is enhanced.

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent applicationserial No. 2010-169889, filed on Jul. 29, 2010, the content of which ishereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a compressor for refrigeration andair-conditioning and a refrigerating and air-conditioning apparatususing a heat pump cycle.

2. Description of Related Art

As the global environment measures in a refrigerating andair-conditioning system field, mention may be made of substitution ofCFC (Chlorofluorocarbons) and HCFC (Hydrochlorofluorocarbons) used asrefrigerants or heat insulating materials as ozone depleting substances,and substitution of HFC (Hydrofluorocarbons) used for enhancement ofefficiency or refrigerants as global warming countermeasures. These havebeen positively pursued.

For substitutes of CFC and HCFC which are ozone depleting substances,selection of refrigerants and heat insulating materials, and developmentof equipment have been pursued with the aims of preventing the depletionof the ozone layer, providing low toxicity and flammability, and beingcapable of ensuring efficiency. As a result, for the heat insulatingmaterials for refrigerators, substitution of the blowing agent fromCFC11 to HCFC141b and cyclopentane has been done in this order.Currently, there has been made a shift to use in combination with avacuum heat insulating material.

The refrigerant was sequentially changed from CFC12C to HFC134a (GWP(Global Warming Potential)=1430) in a refrigerator or a car airconditioner, and was changed from HCFC22 to R410A (HFC32/HFC125 (50/50wt %) mixture: GWP=2088) in a room air conditioner or a package airconditioner.

However, in the third session of the Conference of Parties to the UnitedNations Framework Convention on Climate Change (COP3) held in Kyoto in1997), the HFC emission was to be converted to the CO₂ equivalentemission as a greenhouse gas, to be subject to the regulation.Accordingly, reduction of HFC has come to be pursued.

Thus, in home refrigerators, the amount of a refrigerant charged thereinis small, and flammable refrigerants are also judged as usable from theviewpoint of manufacturing. Accordingly, HFC134a was substituted withflammable R600a (isobutane: GWP=3). Further, attention has currentlyalso been directed to HFC134a for the car air conditioners, and R410Afor room air conditioners and package air conditioners due to agroundswell of popular opinion. Whereas, in industrial refrigerators,the amount of R600a charged is large. Thus, HFC134a is used even atpresent because of a concern about the flammability.

In actuality, by the Home Appliance Recycling Law (Law for Recycling ofSpecified kinds of Home Appliances) enforced in 2001, and theEnd-of-life Vehicle Recycling Law (Act on Recycling, etc. of End-of-lifeVehicles) enforced in 2003, recycling of equipment is obliged. Thus, HFCand the like used as refrigerants are recovered and treated. However, inEU (the European Union), in the 2006 Directive (the Directive2006/40/EC), use of refrigerants with a GWP of more than 150 as therefrigerants for use in car air conditioners was prohibited from thoseshipped in January, 2011. In response to this, the car air conditionerindustry shows various movements. Concerns are rising that R410A will bealso regulated sometime for room air conditioners. There may be reviewof regulations including those on fixed air conditioners in 2011 basedon the EU Directive. This accelerates the study on alternativerefrigerants.

For the alternative refrigerants, 2,3,3,3-tetrafluoropropene (HFO1234yf(Hydrofluoroolefine)) (GWP=4) and 1,3,3,3-tetrafluoropropene (HFO1234ze)(GWP=10) become candidates alone or in mixture thereof because they havethe same thermal physical properties as that of HFC134a, and each have alow GWP, a low toxicity, a low flammability and the like. Therefrigerant to be mixed with 2,3,3,3-tetrafluoropropene is mainlydifluoromethane (HFC32).

Further, it can be also considered that HFC134a or HFC125 is mixedaccording to GWP allowable for low flammability. As other refrigerants,mention may be made of hydrocarbons such as propane and propylene, andlow GWP hydrofluorocarbons such as fluoroethane (HFC161), difluoroethane(HFC152a), and difluoromethane (HFC32).

On the other hand, a refrigerating machine oil is used for a closedelectric compressor, and plays roles of lubrication, sealing, coolingand the like of the sliding part.

For air conditioners, APF (Annual Performance Factor) is adopted as anindex indicating the energy saving performance in accordance with theactual usage by the Energy Saving Law (Law concerning the Rational Useof Energy) revised from 2006. Also for compressors, further saving inenergy and higher efficiency are required. Thus, the use conditionsbecome severe. This results in a demand for a refrigerating machine oilwith good lubricity in view of ensuring the reliability.

As refrigerating machine oils for use in compressors using each singlerefrigerant of 2,3,3,3-tetrafluoropropene (HFO1234yf) and1,3,3,3-tetrafluoropropene (HFO1234ze), or a mixed refrigerant includingthe refrigerants, there are disclosed polyalkylene glycol oils, mineraloils, poly-alpha-olefin oils, and alkylbenzene oils from the foregoingcircumstances (e.g., Japanese Translation of PCT Application No.2009-540170 (Patent Document 1)).

JP-A No. S58-93796 (Patent Document 2) discloses a refrigerating machineoil composition in which a fraction with a boiling point of 50 to 250°C. under ordinary pressure, and a viscosity of 5 centistokes/40° C. orless is contained in a refrigerating machine oil including at least oneof paraffin type refrigerating machine oils, naphthene typerefrigerating machine oils and synthetic refrigerating machine oils.

Other than these, Japanese Translation of PCT Application No.2007-532767 (Patent Document 3), Japanese Translation of PCT ApplicationNo. 2007-538115 (Patent Document 4), Japanese Translation of PCTApplication No. 2008-504374 (Patent Document 5), Japanese Translation ofPCT Application No. 2008-505989 (Patent Document 6), JapaneseTranslation of PCT Application No. 2008-506793 (Patent Document 7),Japanese Translation of PCT Application No. 2008-524433 (Patent Document8) and Japanese Translation of PCT Application No. 2008-239814 (PatentDocument 9) disclose azeotrope-like compositions including HFO-1234yf,HFO-1225yeZ, trans-1,3,3,3-pentafluoropropane (transHFO-1234ze),1,1-difluoroethane (HFC-152a), 1,1,1,2,3,3,3-heptafluoropropane(HFC-227ea), 1,1,1,2-tetrafluoroethane (HFC-134a),1,1,1,2,2-pentafluoroethane (HFC-125) and the like, and lubricants suchas mineral oils (including paraffin oils or naphthene oils), siliconeoil, polyalkylbenzene, polyol ester, polyalkylene glycol, polyalkyleneglycol ester, polyvinyl ether, poly(alpha-olefin) and halocarbon oil.

SUMMARY OF THE INVENTION

2,3,3,3-Tetrafluoropropene (HFO1234yf) and 1,3,3,3-tetrafluoropropene(HFO1234ze) are lower-pressure refrigerants than R410A. Accordingly, itis essential to increase the volume of displacement of the compressorand increase the rotation speed thereof for gaining the circulatingrefrigerant amount. For this reason, in the case of the refrigeratingmachine oils, there remains a problem on the wear resistance in slidingparts such as compressor bearings.

Further, refrigerants such as HFO1234yf, HFO1234ze, propane, propyleneand fluoroethane each have a very high miscibility with therefrigerating machine oils, and the amount of each refrigerant dissolvedin the compressor is large. This results in reduction of the refrigerantdissolved viscosity in the refrigerating machine oil. This unfavorablycauses reduction of the sealing property of the compression part, andfurther an increase in wear amount of the sliding part.

For the foregoing reasons, a refrigerating machine oil capable ofensuring both the improvement of efficiency and the wear resistance ofthe system is preferably used for a refrigerating and air-conditioningapparatus.

It is an object of the present invention to improve the wear resistanceof a compressor for refrigeration and air-conditioning usingrefrigerants for refrigeration and air-conditioning such as refrigerantsincluding 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene and thelike, or hydrocarbons such as propane and propylene, fluoroethane(HFC161), difluoroethane (HFC152a), difluoromethane (HFC32) and R410A asrefrigerants, and to implement a higher efficiency of the refrigeratingand air-conditioning system using the compressor.

The compressor for refrigeration and air-conditioning of the presentinvention includes a mixture charged therein. The mixture includes arefrigerant including 2,3,3,3-tetrafluoropropene,1,3,3,3-tetrafluoropropene or the like; and a refrigerating machine oilincluding a refrigerating machine oil basis such as polyol ester oil,and an additive polyol ester oil. The compressor is characterized inthat the composition of the additive polyol ester oil is 1 to 30 wt %.

In accordance with the present invention, it is possible to obtain acompressor which has achieved both the improvement of the performancesof the compressor and the wear resistance thereof without using aphosphorus-containing extreme pressure agent detrimental to environmentas the additive of the refrigerating machine oil.

Further, in accordance with the present invention, it is possible toobtain an environmentally friendly refrigerating and air-conditioningapparatus capable of achieving both the improvement of performances andthe long-term reliability of the refrigerating and air-conditioningapparatus without using the phosphorus-containing extreme pressure agentas the additive of the refrigerating machine oil.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram showing a room air conditioner.

FIG. 2 is a cross-sectional view showing a scroll type closed compressorfor a room air conditioner.

DETAILED DESCRIPTION OF THE INVENTION

Below, a description will be given to a compressor for refrigeration andair-conditioning in accordance with an embodiment of the presentinvention, and a refrigerating and air-conditioning apparatus using thesame.

The compressor for refrigeration and air-conditioning includes a mixturetherein. The mixture includes a charged refrigerant which is arefrigerant including 2,3,3,3-tetrafluoropropene,1,3,3,3-tetrafluoropropene or difluoromethane, or R410A; and arefrigerating machine oil including a refrigerating machine oil basisincluding at least one base oil selected from the group consisting ofpolyol ester oils expressed by the following chemical formulae (1) and(2) (where in the formulae, R₁ represents an alkyl group having 5 to 9carbon atoms), and an additive polyol ester oil expressed by thefollowing chemical formula (3) (where in the formula, R₂ represents analkyl group having 7 to 9 carbon atoms).

The compressor for refrigeration and air-conditioning is charged with amixture of a charged refrigerant which is a refrigerant including2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, propane,propylene or fluoroethane; and a refrigerating machine oil basisincluding at least one base oil selected from the group consisting ofmineral oils, polyvinyl ether oils, or polyol ester oils expressed bythe chemical formulae (1) and (2) (where in the formulae, R₁ representsan alkyl group having 5 to 9 carbon atoms), the refrigerating machineoil basis having a lower critical solution temperature of −30° C. orless; and an additive polyol ester oil expressed by the chemical formula(3) (where in the formula, R₂ represents an alkyl group having 7 to 9carbon atoms). Then, the composition of the additive polyol ester oil is1 to 30 wt %.

In the compressor for refrigeration and air-conditioning, it isdesirable that a kinetic viscosity at 40° C. of the refrigeratingmachine oil basis is within the range of 25 to 120 mm²/s, and thekinetic viscosity at 40° C. of the additive polyol ester oil is 180mm²/s or more.

The refrigerating and air-conditioning apparatus includes the compressorfor refrigeration and air-conditioning, a heat exchanger for dissipatingthe heat of the charged refrigerant discharged from the compressor forrefrigeration and air-conditioning, a pressure reducing unit forreducing the pressure of the charged refrigerant flowed from the heatexchanger, and a heat exchanger for heating the charged refrigerantreduced in pressure in the pressure reducing unit.

In the refrigerating and air-conditioning apparatus, it is desirablethat a kinetic viscosity at 40° C. of the refrigerating machine oilbasis is 25 to 120 mm²/s, and the adsorption capability of the additivepolyol ester oil to an iron-based material is two or more times higherthan that of the refrigerating machine oil basis.

The compressor for refrigeration and air-conditioning is charged with amixture including a refrigerant for refrigeration and air-conditioningwhich is a refrigerant having a global warming potential of 1000 orless, or R410A; and a refrigerating machine oil including arefrigerating machine oil basis including at least one base oil selectedfrom the group consisting of polyol ester oils expressed by thefollowing chemical formulae (1) and (2) (where in the formulae, R₁represents an alkyl group having 5 to 9 carbon atoms), the refrigeratingmachine oil basis having a kinetic viscosity at 40° C. of 25 to 120mm²/s; and an additive polyol ester oil expressed by the followingchemical formula (3) (where in the formula, R₂ represents an alkyl grouphaving 7 to 9 carbon atoms).

The composition of the additive polyol ester oil is desirably 1 to 30 wt%.

The compressor for refrigeration and air-conditioning includes a scrollor rotary closed compressor including a motor therein, and in addition,a twin rotary compressor, a two-stage compression rotary compressor, anda swing compressor including a roller and a vane integrated with eachother. Desirably, the kinetic viscosity at 40° C. of the refrigeratingmachine oil basis is 25 mm²/s to 120 mm²/s or less, and the kineticviscosity at 40° C. of the additive polyol ester oil is 180 mm²/s ormore.

The compressor for refrigeration and air-conditioning includes a slidingpart formed of an iron-based material. The contact surface pressure inthe sliding part is 10 MPa or more.

In the compressor for refrigeration and air-conditioning, the additivepolyol ester oil has an adsorption capability to the iron-based materialtwo or more times higher than that of the refrigerating machine oilbasis. Further, the adsorption capability of the additive polyol esteroil to the iron-based material is desirably two times higher, andfurther desirably 4 times higher.

The refrigerating and air-conditioning apparatus uses the scroll orrotary compressor.

Below, the present invention will be described in details by way ofExamples.

Examples each disclose a compressor using 2,3,3,3-tetrafluoropropene or1,3,3,3-tetrafluoropropene, or a mixed refrigerant including these, orpropane, propylene, fluoroethane, difluoromethane, or R410A as arefrigerant, and a refrigerating and air-conditioning apparatus usingthe compressor.

In this specification, the refrigerants for refrigeration andair-conditioning include refrigerants with a GWP of 1000 or less such as2,3,3,3-tetrafluoropropene or 1,3,3,3-tetrafluoropropene, or a mixedrefrigerant including these, or propane, propylene, fluoroethane anddifluoromethane, and R410A.

The refrigerating machine oils of Examples include additive polyol esteroils with an extremely higher adsorption capability to an iron-basedmaterial than that of the base oil.

As base oils with a lower adsorption capability than that of theadditive polyol ester oil, mention may be made of mineral oil, polyvinylether oil, and polyol ester oil having an ester group in the molecularstructure.

As the mineral oils, there can be used naphthene type mineral oils andparaffin type mineral oils. As these mineral oils, mention may be madeof, for example, burning oils obtained by refining distillate oilsobtained by subjecting paraffinic crudes, intermediate base crudes, ornaphthenic crudes to atmospheric distillation, or by subjectingatmospherically distilled residual oils to vacuum distillation accordingto the ordinary methods, deeply dewaxed oils obtained by furtherperforming a deep dewaxing treatment after refining, andhydrogen-treated oils obtained by a hydrogen treatment. The refiningmethods at the steps have no particular restriction, and various methodsare used.

The polyol ester oil is obtained from the condensation reaction betweenpolyhydric alcohol and monohydric fatty acid.

The polyol ester oils are preferably of hindered type excellent inthermal stability. Preferred examples of polyhydric alcohols includeneopentyl glycol, trimethylolpropane and pentaerythritol.

Monohydric fatty acids include n-pentanoic acid, n-hexanoic acid,n-heptanoic acid, n-octanoic acid, 2-methylbutanoic acid,2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid,isooctanoic acid, 3,5,5-trimethylhexanoic acid and the like. These areused alone, or in mixture of two or more thereof.

The additive polyol ester oils with a high adsorption capability to aniron-based material are desirably polyol ester oils including estergroups in a large amount in the molecular structure. Mention may be madeof dipentaerythritol of a hindered type synthesized from polyhydricalcohol and monohydric fatty acid.

Monohydric fatty acids include n-pentanoic acid, n-hexanoic acid,n-heptanoic acid, n-octanoic acid, 2-methylbutanoic acid,2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid,isooctanoic acid, 3,5,5-trimethylhexanoic acid and the like. These areused alone, or in mixture of two or more thereof.

The viscosity grade of each refrigerating machine oil for use in theair-conditioning apparatuses and the refrigerating machines of Examplesvaries according to the type of the compressor. However, the kineticviscosity at 40° C. is preferably within the range of 46 to 120 mm²/s ina scroll compressor. Whereas, the kinetic viscosity at 40° C. ispreferably within the range of 25 to 70 mm²/s in a rotary compressor.

The heat resistance class of electrical insulation is specifiedaccording to the heat resistance class of electrical insulation and theheat resistance evaluation JEC-6147 (The Institute of ElectricalEngineers of Japan, Japanese Electrotechnical Committee Standard). Theinsulation materials adopted for compressors for refrigeration andair-conditioning are also selected according to the heat resistanceclass of the standard. However, in the case of the organic insulatingmaterials for the refrigerating and air-conditioning system, theinsulating materials are used in specific environment such as in arefrigerant atmosphere. Therefore, it is necessary to consider theinhibition of deformation and alternation due to pressure other thantemperature. Further, the insulating materials are also in contact withpolar compounds such as refrigerants or refrigerating machine oils.Therefore, a consideration must be also given to solvent resistance,extraction resistance, stabilities concerning thermal, chemical andmechanical properties, refrigerant resistance (crazing (minute pleatedcrack formed upon immersion in a refrigerant after applying a stress tothe film), blister (bubble in a film caused by temperature rising of therefrigerant absorbed in the film)), and the like.

For this reason, it is necessary to use an insulating material of a highheat resistance class (class E 120° C. or more).

The insulating material most frequently used in a compressor is PET(polyethylene terephthalate). As the uses thereof, a film material isused for coil insulation from the iron core of a distributed windingmotor. Fibrous PET is used for the covering material of the coil bindingthread and the lead wire of the motor.

As other insulation film than this, mention may be made of PPS(polyphenylene sulfide), PEN (polyethylene naphthalate), PEEK (polyetherether ketone), PI (polyimide), PA (polyamide) and the like.

Further, for the main insulation covering materials of the coil, thereare used THEIC-modified polyester, polyamide, polyamideimide,polyesterimide, polyesteramideimide and the like. A double coveredcopper wire subjected to double coating of polyesterimide-amideimide ispreferably used.

It does not matter at all if an extreme-pressure additive, an oxidationinhibitor, an acid scavenger, a defoamer, a metal deactivator, and thelike are added to the refrigerating machine oil. Particularly, thepolyol ester oil undergoes degradation caused by hydrolysis in thepresence of moisture. Therefore, mixing of the oxidation inhibitor andthe acid scavenger is essential.

The oxidation inhibitor is preferably DBPC (2,6-di-t-butyl-p-cresol) ofa phenol type.

As the acid scavengers, there are generally used aliphatic epoxy typecompounds and carbodiimide type compounds as compounds having epoxyrings. Particularly, the carbodiimide type compounds are high inreactivity with fatty acids, and trap hydrogen ions dissociated fromfatty acids. Accordingly, the effect of inhibiting the hydrolysisreaction of the polyol ester oil is very large.

As the carbodiimide type compound, mention may be made of bis(2,6-isopropylphenyl) carbodiimide. The amount of the acid scavenger tobe added is preferably set at 0.05 to 1.0 wt % based on the amount ofthe refrigerating machine oil.

Incidentally, an extreme pressure agent may generally be mixed in therefrigerant for use in a compressor. As the extreme pressure agents,there are conventionally used tertiary phosphates such as tricresylphosphate and triphenyl phosphate.

In the compressor for refrigeration and air-conditioning of the presentinvention it is possible to improve the wear resistance by using therefrigerants and the refrigerating machine oils. This eliminates thenecessity of using an extreme pressure agent.

Examples 1 to 12

(Refrigerating Machine Oil Component)

For the enhancement of efficiency of the compressor for refrigerationand air-conditioning, the dissolved viscosity of the refrigerant and therefrigerating machine oil in a mutually dissolved state (which will behereinafter simply referred to as “dissolved viscosity”) is theimportant factor.

A refrigerant whose lower critical solution temperature at whichliquid-liquid double layer separation starts to occur at lowtemperatures is −30° C. or less and a refrigerating machine oil arecombined. In this case, the refrigerant is dissolved in a large amountin the refrigerating machine oil according to the compressor operationconditions. Accordingly, the dissolved viscosity is largely reduced.When the dissolved viscosity in the compressor is low, not only thecompression part sealing property is reduced, but also the oil filmstrength at the compressor sliding part is reduced. Accordingly, wearproceeds, resulting in degradation of the reliability of therefrigerating and air-conditioning apparatus. For this reason, theadsorption property of the refrigerating machine oil component to thesliding part becomes an important parameter.

The large part of the sliding part includes an iron-based material, andon the surface thereof, iron oxide is formed.

The adsorption capability of the refrigerating machine oil to aniron-based material in this specification is substantially considered asthe adsorption capability of the refrigerating machine oil to ironoxide.

Based on this point of view, in the present example, using a Fe₃O₄(triiron tetroxide) powder (specific surface area 1.57 m²/g) with a meanparticle size of 1 μm, the adsorption capability of the refrigeratingmachine oil was evaluated.

The concentrations of the refrigerating machine oil component dilutedwith a solvent before and after adsorption were quantified by nuclearmagnetic resonance spectrometry (NMR). Thus, the amount of the componentadsorbed to the iron oxide powder was calculated. Hexane was used as thesolvent, and adjustment was performed such that each refrigeratingmachine oil component was 0.3 mol-ppm. Into a 20-ml screw tube, the ironoxide powder was collected in an amount of 3 g. Then, a solution of therefrigerating machine oil components was charged in an amount of 10 g.The solution was dispersed for 30 minutes in an ultrasonic washer, andwas allowed to stand for 48 hours. Then, the supernatant liquid wassubjected to 1H-NMR analysis.

Herein, mol-ppm is ppm (parts per million) based on moles. Namely,mol-ppm is ppm calculated with the number of moles of the solution(mixture of solvent and solute) as the denominator and with the numberof moles of the solute as the numerator.

The base oil used as the refrigerating machine oil component is asfollows. Herein, the 40° C. kinetic viscosity means the kineticviscosity at 40° C.

(A) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil ofpentaerythritol type 2-methylhexanoic acid/2-ethylhexanoic acid): 40° C.kinetic viscosity 31.8 mm²/s;

(B) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil ofneopentyl glycol/pentaerythritol type 2-ethylhexanoicacid/3,5,5-trimethylhexanoic acid): 40° C. kinetic viscosity 46.9 mm²/s;

(C) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil ofneopentyl glycol/pentaerythritol type 2-ethylhexanoicacid/3,5,5-trimethylhexanoic acid): 40° C. kinetic viscosity 64.8 mm²/s;

(D) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil ofpentaerythritol type 2-ethylhexanoic acid/3,5,5-trimethylhexanoic acid);40° C. kinetic viscosity 91.3 mm²/s;

(E) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil ofdipentaerythritol type 2-ethylhexanoic acid/3,5,5-trimethylhexanoicacid): 40° C. kinetic viscosity 190 mm²/s;

(F) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil ofdipentaerythritol type 2-ethylhexanoic acid/3,5,5-trimethylhexanoicacid): 40° C. kinetic viscosity 217 mm²/s;

(G) Hindered type polyol ester oil (POE) (dipentaerythritol type3,5,5-trimethylhexanoic acid ester oil): 40° C. kinetic viscosity 417mm²/s;

(H) Polyvinyl ether oil (PVE): 40° C. kinetic viscosity 50.1 mm²/s;

(I) Polyvinyl ether oil (PVE): 40° C. kinetic viscosity 65 mm²/s;

(J) Polyalkylene glycol oil (PAG) (polypropylene glycol dimethyl ether):40° C. kinetic viscosity 112 mm²/s;

(K) Naphthene type mineral oil: 40° C. kinetic viscosity 54.1 mm²/s; and

(L) Poly-alpha-olefin oil: 40° C. kinetic viscosity 61.8 mm²/s

The results of measurement of the adsorption amount of each compound tothe iron oxide powder are shown in Table 1.

TABLE 1 Refrigerating 40° C. kinetic Iron oxide Initial Post-adsorptionAdsorption machine oil viscosity amount concentration concentrationamount component (mm²/s) (g) (mol-ppm) (mol-ppm) (mol/m²) Example 1 A31.8 3.0 0.30 0.255 4.85 × 10⁸ 2 B 46.9 3.0 0.30 0.250 5.39 × 10⁸ 3 C64.8 3.0 0.30 0.260 4.31 × 10⁸ 4 D 91.3 3.0 0.30 0.265 3.77 × 10⁸ 5 E190 3.0 0.30 0.110 2.05 × 10⁻⁷ 6 F 217 3.0 0.30 0.110 2.05 × 10⁻⁷ 7 G417 3.0 0.30 0.130 1.83 × 10⁻⁷ 8 H 50.1 3.0 0.30 0.280 2.16 × 10⁻⁸ 9 I65 3.0 0.30 0.280 2.16 × 10⁻⁸ 10 J 112 3.0 0.30 0.280 2.16 × 10⁻⁸ 11 K54.1 3.0 0.30 0.290 1.08 × 10⁻⁸ 12 L 61.8 3.0 0.30 0.290 1.08 × 10⁻⁸

Each compound shows a different adsorption amount to the iron oxidepowder (adsorption capability). It is indicated that the polar compoundsare more likely to be adsorbed to the iron-based material.

It is indicated that the compounds (E), (F) and (G) each including alarge amount of ester groups present in the molecular structureparticularly exhibit a large adsorption amount in the polar compounds.Namely, the compounds (E), (F) and (G) are 2.0 or more times higher inadsorption capability to an iron-based material (iron oxide) than otherrefrigerating machine oil components (A) to (D) and (H) to (L).

This indicates that the refrigerating machine oil components (E), (F)and (G) each tend to form a film at the compressor sliding part.

This is considered to be due to the following reason.

The oxygen of carbonyl (C=0) included in an ester group tends to benegatively charged. In contrast, the surface of iron oxide is generallyhydrated to be in a structure having a hydroxyl group. For this reason,the attractive force due to the Coulomb force is generated between thehydrogen included in the hydroxyl group in the surface of the iron oxideand the oxygen included in the ester group, which facilitatesadsorption.

From the results, (E), (F) and (G) were determined to be used asadditive polyol ester oils in the present invention.

Examples 13 to 25

A refrigerant and a refrigerating machine oil are charged in thecompressor for refrigeration and air-conditioning.

The compatibility between the refrigerant and the refrigerating machineoil is one of important characteristics in terms of ensuring thereliability of the compressor such as oil return from the refrigerationcycle to the compressor (ensuring the oil amount inside the compressor)or reduction of the heat exchange efficiency. However, the dissolvedviscosity of the liquid mixture largely varies according to the amountof the refrigerant dissolved in the refrigerating machine oil due to thepresence of the refrigerant. A large dissolution amount results in aremarkable reduction of the viscosity of the oil. Accordingly, asufficient oil film strength cannot be obtained at the sliding part.Further, the function as the sealing material of the compression part isimpaired.

The compatibility between the refrigerant and the refrigerating machineoil was evaluated and measured according to JIS K 2211.

In a pressure resistant glass container, the refrigerant was charged ata given oil concentration. Thus, the temperature was changed to observethe contents. At this step, when the contents became whitish, thecontents were determined as having undergone two-layer separation. Fortransparency, the contents were determined as having undergonedissolution. The oil concentration dependency of the temperature atwhich two-layer separation occurs is generally a curve having a maximumvalue. This maximum value is referred to as a lower critical solutiontemperature. The lower critical solution temperature is a parameterindicating the degree of the compatibility between the refrigerant andthe refrigerating machine oil.

The refrigerating machine oil compatible with each refrigerant wasselected. Thus, the results of measurement of the lower criticalsolution temperature are shown in Table 2.

TABLE 2 40° C. Refrigerating kinetic Lower critical machine oilviscosity solution Refrigerant component (mm²/s) temperature Example 13HFO1234yf C 64.8 −60° C. or less 14 HFO1234yf I 65 −60° C. or less 15Propane C 64.8 −60° C. or less 16 Propane K 54.1 −60° C. or less 17Propylene C 64.8 −60° C. or less 18 Propylene K 54.1 −60° C. or less 19HFC161 C 64.8 −60° C. or less 20 HFC161 I 65 −60° C. or less 21 HFC161 K54.1 −40° C. 22 HFC32 C 64.8 20° C. or more 23 HFC32 I 65 20° C. or more24 R410A C 64.8    9° C. 25 R410A I 65 −47° C.

The lower critical solution temperature largely varies according to thedegree of compatibility between the refrigerant and the refrigeratingmachine oil. Particularly, when HFO1234yf, propane, propylene orfluoroethane is used as the refrigerant, the solubility in therefrigerating machine oil is very high, which causes a large reductionof the viscosity in the operation conditions of the compressor.Generally, the viscosity grade of the refrigerating machine oil isincreased to take countermeasures thereagainst. However, the amount ofthe refrigerant dissolved increases according to the temperature andpressure in the operation conditions of the compressor for refrigerationand air-conditioning. Accordingly, in actuality, the viscosity does notincrease largely.

Examples 26 to 31 and Comparative Examples 1 to 6

Using a shell type four-ball friction-wear tester, the lubricity of therefrigerating machine oil was evaluated.

Using a ½-inch SUJ2 steel ball as a specimen, the wear scar diameter(average of 3 balls) and the coefficient of friction of each fixedspecimen after performing the test under load: 280 N, temperature: 120°C., rotation speed: 1200 min⁻¹, and time: 10 min were measured.

As the refrigerating machine oil bases, there were used the polyol esteroils (A) to (D), the polyvinyl ether oil (I), and the naphthene typemineral oil (K). The mixtures obtained by adding the additive polyolester oil (F) in an amount of 5.0 wt % thereto were evaluated.

As Comparative Examples, evaluation was made on the cases of the polyolester oils (A) to (D) used alone, the case of the polyvinyl ether oil(I) used alone, and the case of the naphthene type mineral oil (K) usedalone.

The results of evaluation of the lubricity of each refrigerating machineoil are shown in Table 3.

TABLE 3 Refrigerating 40° C. machine oil kinetic Wear scar componentviscosity diameter Coefficient Basis Additive (mm²/s) (mm) of frictionExample 26 A F (5 wt %) 34.7 0.57 0.23 27 B F (5 wt %) 50.4 0.51 0.22 28C F (5 wt %) 68.6 0.49 0.23 29 D F (5 wt %) 95.2 0.48 0.21 30 I F (5 wt%) 68.9 0.46 0.18 31 K F (5 wt %) 57.5 0.45 0.18 Compar- 1 A None 31.80.62 0.36 ative 2 B None 46.9 0.57 0.35 Example 3 C None 64.8 0.58 0.354 D None 91.3 0.55 0.33 5 I None 65 Seizure Seizure occurred occurred 6K None 54.1 Seizure Seizure occurred occurred

The results indicate the following: for the refrigerating machine oilsnot including the additive polyol ester oil (F) mixed therein ofComparative Examples 1 to 4, each wear scar diameter is large, and eachcoefficient of friction is high; for Comparative Examples 5 and 6, thetest was stopped because of the occurrence of seizure immediately afterthe start of the test.

In contrast, for the refrigerating machine oils each including theadditive polyol ester oil (F) mixed therein shown in Examples 26 to 31,each wear scar diameter and each coefficient of friction were suppressedregardless of the oil species of the refrigerating machine oil basis.Thus, the lubricity improving effect was produced. This is due to thefollowing fact. The adsorption capability of the additive polyol esteroil (F) to the iron-based material is larger than that of therefrigerating machine oil basis. Accordingly, the friction surface wasrendered in a low surface energy state. This produced the wearresistance and an effect of reducing the coefficient of friction. Alsowhen the refrigerating machine oil bases were the polyvinyl ether oil(I) and the naphthene type mineral oil (K), seizure did not occur.Particularly, when the refrigerating machine oil basis is the polyvinylether oil (I) or the naphthene type mineral oil (K) exhibiting a smalleradsorption amount than that of the additive polyol ester oil (F) asshown in Table 1, the additive polyol ester oil (F) becomes more likelyto be adsorbed on the friction surface. For this reason, the lubricityimproving effect tends to be produced.

Examples 32 to 37 and Comparative Examples 7 to 8

In order to observe the effects of the additive polyol ester oils (E)and (G), the same test as in Example 26 was performed using the shelltype four-ball friction-wear tester, except for changing the type andthe addition amount of the additive polyol ester oil.

The results of evaluation of the lubricity of each refrigerating machineoil are shown in Table 4.

TABLE 4 Refrigerating 40° C. machine oil kinetic Wear scar Co- componentviscosity diameter efficient Basis Additive (mm²/s) (mm) of frictionExample 32 C F (1 wt %) 65.5 0.52 0.23 33 C F (10 wt %) 72.7 0.48 0.2234 C F (20 wt %) 81.7 0.49 0.23 35 C F (30 wt %) 91.9 0.48 0.21 36 C E(5 wt %) 68.2 0.51 0.25 37 C G (5 wt %) 70.6 0.52 0.25 Compar- 7 C F(0.1 wt %) 64.9 0.58 0.35 ative 8 C F (0.5 wt %) 65.2 0.57 0.33 Example

For the refrigerating machine oils of Examples 32 to 37 shown in thistable, as compared with the refrigerating machine oil using (C) as therefrigerating machine oil basis, and not including an additive addedthereto of Comparative Example 3 (shown in Table 3), the wear scardiameter and the coefficient of friction were suppressed. Thus, it waspossible to observe the lubricity improving effect.

Whereas, in the cases of Comparative Examples 7 and 8 each having asmall amount of the additive polyol ester oil (F) added therein, eachwear scar diameter is large, and each coefficient of friction is high.Accordingly, the lubricity improving effect is less likely to beexerted. In contrast, for the refrigerating machine oils in each ofwhich the additive polyol ester oil (F) is added in an amount of 1.0 wt% or more based on the amount of the refrigerating machine oil basisshown in Examples 32 to 35, each wear scar diameter and each coefficientof friction are suppressed. This produced the lubricity improvingeffect.

Examples 38 and 39, Comparative Examples 9 and 10

FIG. 1 shows the outline of a dual-purpose cooling/heating room airconditioner used in the present Examples.

When an inside of a room is cooled, a high-temperature high-pressurerefrigerant gas (charged refrigerant) adiabatically compressed through adischarge pipe of a compressor 1 passes through a four-way valve 2 to becooled in an outdoor heat exchanger 3 (used as a condensing means),resulting in a high-pressure liquid refrigerant. The refrigerant isexpanded in an expansion means 4 (such as a capillary tube or atemperature type expansion valve, which is also referred to as apressure reducing unit), resulting in a low-temperature low-pressuresolution slightly containing a gas. The solution reaches the indoor heatexchanger 5 (used as an evaporation means), and gets heat from the airinside the room, resulting in a low-temperature gas form. The resultinggas passes through the four-way valve 2 again, and reaches thecompressor 1. When the inside of the room is heated, the flow of therefrigerant is changed to the opposite direction by the four-way valve2, resulting in the adverse effect. In the present example, a scrollcompressor was used as the compressor.

FIG. 2 shows the schematic structure thereof.

In the compressor, a spiral wrap 8 standing upright on an end plate 7 ofa fixed scroll member 6, and a rotary scroll member 9 having a wrap 10in substantially the same shape as that of the fixed scroll member 6 areengaged with the wrap 8 and the wrap 10 facing each other. As a result,a compression mechanism part is formed. And the rotary scroll member 9is caused to undergo rotary movement by a crank shaft 11. A compressionchamber situated on the outermost side of compression chambers 12 a and12 b formed by the fixed scroll member 6 and the rotary scroll member 9moves toward the central part formed of the fixed scroll member 6 andthe rotary scroll member 9 while gradually shrinking in volume with therotary movement. When the compression chambers 12 a and 12 b reach thevicinity of the central part including the fixed scroll member 6 and therotary scroll member 9, the compression chambers 12 a and 12 bcommunicate with the discharge port 13. Accordingly, the compressed gasin the compression chambers 12 a and 12 b is discharged through thedischarge pipe 16 to the outside of the compressor.

In the compressor of the present example, an electric motor 17 isincluded in a pressure vessel 15. Thus, the compressor performs acompression operation by rotation of the crank shaft 11 at a givenconstant speed or at a rotation speed according to the voltagecontrolled by an inverter not shown. Further, an oil reservoir part 20is provided below the motor 17. The oil in the oil reservoir part 20passes through an oil path 19 provided in the crank shaft 11 due to thedifference in pressure, and is subjected to lubrication of the slidingpart between the rotary scroll member 9 and the crank shaft 11, asliding bearing 18 and the like.

In Examples 38 and 39 and Comparative Examples 9 and 10, the indoor unitwas set in a thermostatic chamber (35° C., humidity 75%) to perform anactual equipment test of 2160-hour operation using the room airconditioner shown in FIG. 1.

A heat-resistant PET film (type B 130° C.) was used for coil insulationfrom the iron core of the motor 17. There was used a double coveredcopper wire subjected to double coating of polyesterimide-amideimide forcoil main insulation.

For evaluation of the room air conditioner, attention was given to thewear state of the scroll compressor. Thus, there was measured theclearance increment due to wear from the frame 14 to the crank shaft 11(between the frame 14 and the crank shaft 11) before and after the test.A larger clearance increment from the frame 14 to the crank shaft 11(which will be hereinafter also referred to as between the frame and theshaft) indicates a larger wear amount. Generally, as the clearanceincrement increases, vibration and noise increase.

HFO1234yf (2,3,3,3-tetrafluoropropene) was used alone as therefrigerant. The HFO1234yf is a low-pressure refrigerant. The amount ofcirculating refrigerant is small, resulting in an increase in pressureloss in piping. For this reason, evaluation was conducted in thefollowing manner: the displacement amount of the compressor was set attwo times higher than usual, and the diameter of the connection pipingwas increased, and the number of paths of the heat exchanger wasincreased; thus, the distribution balance was adjusted.

In a refrigerating and air-conditioning cycle using HFO1234yf andHFO1234ze, and a mixed refrigerant including these, the compatibilitybetween the refrigerant and the refrigerating machine oil becomes animportant characteristic for ensuring the amount of oil to be returnedto the compressor. In the refrigerating and air-conditioning cycle, itis necessary that the refrigerating machine oil also circulates as withthe refrigerant. When the compatibility is inferior, the refrigeratingmachine oil discharged by a mechanical element from the compressor doesnot circulate. Accordingly, the oil separated particularly at thelow-temperature part is retained, resulting in a smaller oil amount ofthe compressor. This hinders the lubricating oil of the sliding part.For this reason, it is preferable that the refrigerant and therefrigerating machine oil are dissolved within the operating conditiontemperature range in the cycle.

With respect to HFO1234yf, hydrocarbon oils such as naphthene typemineral oils, paraffin type mineral oils, alkylbenzene oils andpoly-alpha-olefin oils are less likely to be miscible. Therefore, apolyol ester oil or a polyvinyl ether oil is preferable.

In Example 38, evaluation was performed using the refrigerating machineoil ((C)+(F)) adopted in Example 28 having compatibility with HFO1234yf.Whereas, in Example 39, evaluation was performed using the refrigeratingmachine oil ((I)+(F)) adopted in Example 30.

As the refrigerating machine oil basis, the oil (C) or (I) was used. Theoil (F) having a high adsorption capability thereto is mixed in anamount of 5 wt % therein. Thus, there was carried out a test with arefrigerating machine oil having a kinetic viscosity at 40° C. set at68.6 mm²/s or 68.9 mm².

In Comparative Examples 9 and 10, the test was carried out with only therefrigerating machine oil bases in each of which the additive polyolester oil in Examples 38 and 39 was not added.

As the target value of this test, the clearance increment due to wearbetween the frame and the shaft after the test is 10 μm or less.

The results of Examples 38 and 39 and Comparative Examples 9 and 10 areshown in Table 5.

TABLE 5 Refrigerating machine oil 40° C. kinetic Sliding bearingcomponent viscosity Clearance Cooling intermediate conditionsRefrigerant Basis Additive (mm²/s) increment (μm) Viscosity (mPa · s)COP(%) Example 38 HFO1234yf C F (5 wt %) 68.6 3 1.8 101 (Ratio based onreference 1) 39 HFO1234yf I F (5 wt %) 68.9 4 2.2 101.5 (Ratio based onreference 1) 40 R290 C F (5 wt %) 68.6 5 2.0 102 (Ratio based onreference 2) 41 R290 K F (5 wt %) 57.5 6 1.5 101 (Ratio based onreference 2) 42 R410A C F (5 wt %) 68.6 2 3.8 101 (Ratio based onreference 3) Comparative 9 HFO1234yf C None 64.8 12 1.2 100(Reference 1) Example 10 HFO1234yf I None 65 18 1.3 100 (Ratio based onreference 1) 11 R290 C None 68.6 15 1.1 100 (Reference 2) 12 R290 K None57.5 24 0.9 98 (Ratio based on reference 2) 13 R410A C None 68.6 8 3.7100 (Reference 3)

As apparent from Table 5, for the room air conditioners of Examples 38and 39, as compared with Comparative Examples 9 and 10, the frame-shaftclearance increment can be largely reduced. Accordingly, wear isinhibited. As a result, high reliability can be obtained in the room airconditioner.

Further, in Table 5, regarding each combination of the refrigerants andthe refrigerating machine oils, the measurement results of the viscosityand an efficiency in a cooling intermediate conditions are also shown.

For the measurement of the viscosity, a piston type viscometer fromJapan Controls Co., Ltd. was used.

Further, the efficiency is expressed as the ratio using Coefficient ofPerformance (COP) with Comparative Example 9 as the reference (100).

The results indicate as follows. In Comparative Examples 9 and 10,reduction of the viscosity occurred, so that a sufficient sealingproperty could not be obtained at the compression part. In contrast, theviscosity increased in Examples 38 and 39.

Further, as shown in Examples 28 and 30 of Table 3, the frictioninhibiting effect due to the additive polyol ester oil was exhibited.Accordingly, the coefficient of performance was improved as comparedwith Comparative Example 9 (reference From the results of Examples up tothis point, it has been indicated that there can be obtained arefrigerating and air-conditioning apparatus capable of inhibiting wearof the compressor, and sufficiently ensuring the long-term insulationreliability.

Further, although not shown, evaluation was performed by the same actualequipment test with a combination of a mixed refrigerant of HFO1234yfand HFC32 (20 wt % and 40 wt %) for the refrigerant and therefrigerating machine oil ((C)+(F)) adopted in Example 28. As a result,roughly the same results as those of Examples 38 and 39 were obtained.This has indicated that even use of a mixed refrigerant can produceeffects, and produces no problem.

Examples 40 to 42 and Comparative Examples 11 to 13

In Examples 40 to 42, propane and R410A were used for the refrigerant.Thus, refrigeration cycles in accordance with respective refrigerantswere prepared to perform the same actual equipment test as that ofExample 38.

In Example 40, there were used propane as the refrigerant, and arefrigerating machine oil including the oil (C) as the refrigeratingmachine oil basis, and the oil (F) as an additive polyol ester oil mixedin an amount of 5.0 wt % therein.

In Example 41, there were used propane as the refrigerant, and arefrigerating machine oil including the oil (K) as the refrigeratingmachine oil basis, and the oil (F) as an additive polyol ester oil mixedin an amount of 5.0 wt % therein.

In Example 42, there were used R410A as the refrigerant, and arefrigerating machine oil including the oil (C) as the refrigeratingmachine oil basis, and the oil (F) as an additive polyol ester oil mixedin an amount of 5.0 wt % therein. In Comparative Examples 40 to 42,evaluations were respectively made on the refrigerating machine oilseach not including the additive polyol ester oil added therein.

The evaluation results are shown in Table 5.

Propane has a high solubility in polyol ester oil, mineral oil or thelike as shown in the evaluation results of the compatibility of Table 2.This causes a large reduction of viscosity in the compressor. Further,propane does not contain a halogen atom in the molecular structure, andhence does not form iron halide contributing to the lubricity at afriction-generating site. This results in a large increase in clearanceincrement due to friction between the frame and the shaft as shown inComparative Examples 11 and 12.

In contrast, as shown in Examples 40 and 41, for the combinationincluding the additive polyol ester oil (F) mixed to the refrigeratingmachine oil basis, the clearance increment due to the wear between theframe and the shaft was largely reduced, resulting in ease of friction.As a result, the Coefficient of Performance (COP) improved as comparedwith Comparative Example 11 (reference 2).

Further, in Example 42 using R410A as the refrigerant, as compared withComparative Example 13 (reference 3), the clearance increment due to thewear between the frame and the shaft was suppressed, and the Coefficientof Performance (COP) also improved.

This indicates that even refrigerants such as difluoromethane,fluoroethane and propylene can provide the same effects regardless ofthe type of the refrigerant.

Other than these, the same effects can also be produced by a rotarycompressor, a twin rotary compressor, a two-stage compression rotarycompressor, and a swing compressor including a roller and a vaneintegrated with each other.

The present invention is applicable to a refrigerant compressor for arefrigerating and air-conditioning apparatus, and a refrigerating andair-conditioning apparatus.

1. A compressor for refrigeration and air-conditioning, comprising amixture charged therein, the mixture comprising: a charged refrigerantwhich is a refrigerant including 2,3,3,3-tetrafluoropropene,1,3,3,3-tetrafluoropropene or difluoromethane, or R410A; and arefrigerating machine oil comprising a refrigerating machine oil basisincluding at least one base oil selected from the group consisting ofpolyol ester oils expressed by the following chemical formulae (1) and(2) (where in the formulae, R₁ represents an alkyl group having 5 to 9carbon atoms), and an additive polyol ester oil expressed by thefollowing chemical formula (3) (where in the formula, R₂ represents analkyl group having 7 to 9 carbon atoms), a composition of the additivepolyol ester oil being 1 to 30 wt %.


2. The compressor according to claim 1, wherein a kinetic viscosity at40° C. of the refrigerating machine oil basis is within the range of 25to 120 mm²/s, and the kinetic viscosity at 40° C. of the additive polyolester oil is 180 mm²/s or more.
 3. A refrigerating and air-conditioningapparatus comprising the compressor according to claim 1, a heatexchanger for dissipating the heat of the charged refrigerant dischargedfrom the compressor, a pressure reducing unit for reducing the pressureof the charged refrigerant flowed from the heat exchanger, and a heatexchanger for heating the charged refrigerant reduced in pressure in thepressure reducing unit.
 4. The refrigerating and air-conditioningapparatus according to claim 3, wherein an adsorption capability of theadditive polyol ester oil to an iron-based material is two or more timeshigher than that of the refrigerating machine oil basis.
 5. A compressorfor refrigeration and air-conditioning, comprising a mixture chargedtherein, the mixture comprising: a charged refrigerant which is arefrigerant including 2,3,3,3-tetrafluoropropene,1,3,3,3-tetrafluoropropene, propane, propylene or fluoroethane; and arefrigerating machine oil comprising a refrigerating machine oil basisincluding mineral oils or polyvinyl ether oils, or at least one base oilselected from the group consisting of polyol ester oils expressedby thefollowing chemical formulae (1) and (2) (where in the formulae, R₁represents an alkyl group having 5 to 9 carbon atoms), the refrigeratingmachine oil basis having a lower critical solution temperature of −30°C. or less, and an additive polyol ester oil expressed by the followingchemical formula (3) (where in the formula, R₂ represents an alkyl grouphaving 7 to 9 carbon atoms), a composition of the additive polyol esteroil being 1 to 30 wt %.


6. The compressor according to claim 5, wherein a kinetic viscosity at40° C. of the refrigerating machine oil basis is within the range of 25to 120 mm²/s, and the kinetic viscosity at 40° C. of the additive polyolester oil is 180 mm²/s or more.
 7. A refrigerating and air-conditioningapparatus comprising the compressor according to claim 5, a heatexchanger for dissipating the heat of the charged refrigerant dischargedfrom the compressor, a pressure reducing unit for reducing the pressureof the charged refrigerant flowed from the heat exchanger, and a heatexchanger for heating the charged refrigerant reduced in pressure in thepressure reducing unit.
 8. The refrigerating and air-conditioningapparatus according to claim 7, wherein an adsorption capability of theadditive polyol ester oil to an iron-based material is two or more timeshigher than that of the refrigerating machine oil basis.
 9. A compressorfor refrigeration and air-conditioning comprising a mixture chargedtherein, the mixture comprising: a refrigerant for refrigeration andair-conditioning which is a refrigerant with a global warming potentialof 1000 or less, or R410A; and a refrigerating machine oil comprising arefrigerating machine oil basis including at least one base oil selectedfrom the group consisting of polyol ester oils expressed by thefollowing chemical formulae (1) and (2) (where in the formulae, R₁represents an alkyl group having 5 to 9 carbon atoms), the refrigeratingmachine oil basis having a kinetic viscosity at 40° C. of 25 to 120mm²/s, and an additive polyol ester oil expressed by the followingchemical formula (3) (where in the formula, R₂ represents an alkyl grouphaving 7 to 9 carbon atoms), a composition of the additive polyol esteroil being 1 to 30 wt %.


10. A refrigerating and air-conditioning apparatus comprising thecompressor according to claim 9, a heat exchanger for dissipating theheat of the refrigerant discharged from the compressor, a pressurereducing unit for reducing the pressure of the refrigerant flowed fromthe heat exchanger, and a heat exchanger for heating the refrigerantreduced in pressure in the pressure reducing unit.
 11. The refrigeratingand air-conditioning apparatus according to claim 10, wherein anadsorption capability of the additive polyol ester oil to an iron-basedmaterial is two or more times higher than that of the refrigeratingmachine oil basis.